Cam selection mechanism for zigzag sewing machines



July 2, 1968 J. COULOMBE CAM SELECTION MECHANISM FOR ZIGZAG SEWING MACHINES Filed May 4, 1966 4 Sheets-Sheet 1 INVENTOR. Lione'l J. Coulombe BY i 2TTORNE Y- lllllllllll lI||||||||||l ||||||||||-...L

y 2, 1963 I J. COULOMBE 3,390,651

CAM SELECTION MECHANISM FOR ZIGZAG SEWING MACHINES Filed May 4, 1966 4 Sheets-Sheet 2 Fig.3.

INVENTOR. Lionel J. Coulombe with: BY

40mm! Tea" J TTORNEY y 1968 L. J. COULOMBVE 3,390,651

CAM SELECTION MECHANISM FOR ZIGZAG SEWING MACHINES Filed May 4, 1966 4 Sheets-Sheet 5 INVENTOR. Lionel J. Coulombe WIMOSS' ATTORNEY #09411 eai y -9 L. .J. COULOMBE I 3,390,651

CAM SELECTION MECHANISM FOR ZIGZAG SEWING MACHINES Filed May' 4, 1966 4 Sheets-Sheet 4 INVENTOR. Lionel J; Coulombe witness salfiIfgqi TTORNEY United States Patent 3,390,651 CAM SELECTION MECHANISM FOR ZIGZAG SEWING MACHINES Lionel J. Coulombe, Matawan, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed May 4, 1966, Ser. No. 547,468 6 Claims. (Cl. 112158) This invention relates to zigzag sewing machines, and more particularly to a novel and improved cam selection mechanism for a zigzag sewing machine employing a stack of pattern cams for automatically controlling the sequence of zigzag stitch formation.

The present invention is an improvement over the cam selection mechanism disclosed in the United States Patent No. 3,191,559, June 19, 1965', to which reference may be had for a more complete understanding of this invention.

It is an object of this invention to provide a novel and improved means operated by the initial actuation of the ca m selector mechanism for releasing the bias on a cam follower mechanism to permit cam selection.

It is an object of this invention to provide a bias release means for the cam follower mechanism of the above character which is automatically re-established when the machine is operated, but in which the bias may be released in any position of the sewing machine actuating mechanism.

In order to produce the highest quality stitch formation using a sewing machine, it is recognized in the art that the needle aperture in the sewing machine throat plate ought to be as small as is possible in order to accommodate penetration of the needle. If the throat plate needle aperture is larger than is necessary, flagging of the work occurs, i.e. the work fabric is not restrained against movement with the needle as well as it could be, and such flagging results in a deterioration in the uniformity with which the stitches are set into the work. It is well known, therefore, in sewing machines which are capable of sewing either zigzag or straight lines of stitches, to utilize a throat plate with a laterally elongate needle aperture only when sewing zigzag stitches, and when high quality straight stitches are desired, to substitute a throat plate having a round needle aperture closely conforming to the fixed path of the needle reciprocation during straight stitching.

When a cam selection system is utilized which releases the bias on the cam follower mechanism during cam selection and then automatically re-establishes the bias when the machine is operated, a problem has existed when the cam follower mechanism is set to produce straight stitches and a throat plate with a round needle aperture is substituted. The problem is that until the bias is re-established by operation of the machine, the cam follower mechanism may not conform to the cam intelligence dictating straight stitching and the needle is apt to be broken because on the first needle penetration the needle may not follow a path of reciprocation coincident with the round needle aperture.

It is an object of this invention to provide a unique auxiliary biasing means for the cam follower mechanism which is effective only when the cam follower mechanism is set to produce straight stitching but which becomes effective immediately upon selection of the straight stitch position of the cam follower mechanism and does not require further operation of the sewing machine for effectiveness.

With the above and additional objects and advantages in view, as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of 3,399,651 Patented July 2, 1968 parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 is a top plan view of a sewing machine embodying the present invention, the top cover plate of the machine being removed and portions of the machine frame being broken away to illustrate the mechanism,

FIG. 2 is a vertical cross sectional view of a portion of the mechanism of this invention taken lengthwise of the machine substantially along line 22 of FIG. 1,

FIG. 3 is a vertical cross sectional view taken transversely of the machine substantially along line 33 of FIG. 1,

FIG. 4 is a vertical cross sectional view taken transversely of the machine substantially along line 4--4 of FIG. 1,

FIGS. 5, 6 and 7 represent bottom plan views of the bias release and re-establishment means of the machine of FIG. 1 with FIG. 5 illustrating the position of parts with the bias established, FIG. 6 with the bias released during cam selection, and FIG. 7 with the bias being reestablished,

FIGS. SA, 6A, and 7A represent vertical cross sectional views of the bias release and re-establishment means taken substantially along line 44 of FIG. 1 and illustrating the position of the parts corresponding to that illustrated in FIGS. 5, 6 and 7 respectively, and

FIG. 8 is a top plan view of a portion of the machine of FIG. 1 illustrating the cam selector mechanism occupying a position dictating the straight stitch position of the cam follower mechanism.

With reference to the drawings, there is illustrated a sewing machine having a frame 1 including a bracket arm 2, a head 3, and a panel 4 in the front face of the bracket arm 2, such as disclosed and claimed in the United States patent application of H. Dreyfuss, Ser. No. 99,252 filed Mar. 29, 1961, now Patent No. 3,150,623. Mounted in the head 3 for endwise reciprocation and for vibration laterally of the line of stitch formation, or in other words, for zigzag movements, is a needle bar 5. Lateral vibration is imparted to the needle bar 5 by a bracket 6 pivotally mounted intermediate its ends on the presser bar bushing 7, the opposite arms of the bracket 6 being connected to the needle bar 5 and to one end of an endwise movable pitman 8 whereby upon actuation of the pitman, lateral vibration is imparted to the needle bar. The opposite end of the pitman 8 carries a wobble plate 9 pivotally mounted thereon by a pivot pin 10.

The plate 9 and thus the pitman 3 and the needle bar mechanism are biased toward the right, as seen in FIG. 1, by a bias element or spring 11 connected at one end to the pitman 8 at a point adjacent to its connection with the bracket 6 and anchored at the other end to the end of a lever 12. There is also provided a spring 13 anchored on the lever 12, which spring acts upon an arm 14 pivotally mounted in the frame on a post 15, the free end of which arm 14 bears lightly against the plate 9 to resist over-throw thereof. The plate 9 is thus biased against the cam followers 16 and 17 which are in turn biased into tracking engagement with any selected ones of the cams in a cam stack 18. The cam stack 18 is mounted for rotation on a vertical post 19 and rotation is imparted thereto by a worm wheel 20 on the stack that cooperates with a worm 21 on the main shaft 22 ice which is journaled longitudinally of the bracket arm 2.

The pitman 8 is adapted to be shifted to place the pivot pin 10 alternatively substantially over the points of contact between the plate 9 and followers 16 and 17 or at points between these two positions, thereby adjusting the amount of the cam-induced motion of the followers 16 and 17 that is transmitted to the plate 9 and thus to the pitman 8 and the needle bar mechanism. The means 3 for shifting the pitman comprises a lever 23 having a handle portion 24 extending through a slot 25 in the panel 4 to be accessible to the operator. The lever 23 is pivotally adjustable about the post 19 and is connected to the end of the pitman 8 by a ball and socket connection 26.

To provide for placing the followers 16 and 17 in tracking engagement with a selected one of the cams in the cam stack 13, each of the followers are pivotally mounted and are slidable endwise on posts 28 and 29, respectively, which are parallel to the axis of the cam stack 18. The post 28 is provided with a plurality of notches 30, each corresponding to one of the individual cams in the cam stack 18, which notches are adapted to be entered selectively by a knife-like element 31 that extends through a slot in the hub 32 of the follower 16 and into the notch, thus positioning the follower 16 and locking the same endwise of the post 23 with respect to the selected one of the cams. Similarly, the post 29 has a plurality of notches 33 adapted to be entered by a knife-like element 34 extending through a slot in the hub 35 of the follower 17.

In the normal manner, to effect cam selection with either of the followers 16 or 17, the respective knife-like element 31 or 34 is retracted from the notches in the post to free the follower for endwise movement, but without retracting the same from the hub of the follower. Thus, as the element 31 or 34 is moved, the respective follower will be moved with it. At the same time, the cam-engaging portion of the follower is lifted clear of the cams so that it can be moved freely along the cam stack.

With respect to the follower 16, the cam selector mechanism comprises a shaft 36 rotatably and slidably mounted in the frame by means of a lug 37 and a bushing 38 in the rear wall of the frame that receives the end of the shaft 36. Secured to the shaft 36 is a crank arm 40 that carries the knife-like element 31 and which is adapted to abut against an arm 41 integral with the follower 16. Thus, as the shaft 36 is moved endwise inwardly, the element 31 is moved out of the notches and the follower 16 is pivoted so that the cam engaging end thereof is clear of all of the cams. The shaft 36 can then be turned to move the follower 16 along the stack to a position opposite any selected cam. The means for moving and for turning the shaft 36 comprises an actuating arm 42 secured to the shaft 36 and having a handle portion 43 extending through the panel 4 to the exterior of the machine. Movement of the shaft 36 inwardly is limited by engagement of the crank arm 40 with the bushing 38. A coil spring 44 is disposed between the arm 40 and the frame to force the shaft 36 outwardly when it is released, this motion being limited by seating of the element 31 in the notch 30.

With respect to the follower 17, the cam selection mechanism comprises a bracket 45 slidably and rotatably mounted on the shaft 36 and having an actuating arm 46 that extends through the panel 4 and terminates in a handle portion 47. The bracket 45 has a crank arm 48 carrying a knife-like element 34 which is adapted to abut against an arm 49 integral with the follower 17. Thus, when the bracket 45 is forced inwardly, the element 34 is withdrawn from the slot 33 and the cam engaging end of the follower 17 is lifted clear of the cams in the stack 18. When the bracket is then turned by manipulation of the handle 47, the follower 17 is shifted endwise of the post 29. When the handle 47 is released, a spring 50 biases the bracket 45 to its normal position. Endwise movement of the bracket 45 on the shaft 36 is limited by a stop finger 51 secured to the machine frame.

In view of the fact that the cam followers are biased by the springs 11 and 13 into track-ing engagement with the cams, lifting the cam engaging end of the cam follower would normally require that the follower be lifted against the spring action. The present invention is directed to facilitating cam selection and this is accomplished by rendering the springs 11 and 13 inoperative or relaxing the same during cam selection, thereby eliminating the necessity of holding the follower raised against the action of the springs 11 and 13 while effecting cam selection. To this end, the springs 11 and 13 are anchored to the lever 12 which is universally pivoted intermediate its ends by a pivot pin 52 mounted in an element 53 having a stud 54 on an axis normal to the axis of the pin 52 and journaled for turning in a mounting plate 55 in the frame, whereby the lever 12 is pivotally movable about the axis of the stud 54 to provide for stressing and relaxing the spring and is pivotally movable about the axis of the pin 52 to provide for latching and unlatching the same.

The lever 12 is latched in the position in which the springs 11 and 13 are stressed, and to provide for such latching, a latch block 60 is pivotally secured on a fulcrum stud 61 beneath the mounting plate 55.

Referring to FIGS. 5 t0 7 and the companion FIGS. 5A to 7A that end of the lever 12 to which the spring 11 is attached is considerably longer than the opposite extremity 62 which cooperates with the latch block, and therefore, gravity urges the longer extremity downwardly and the lever extremity 62 is urged upwardly toward the undersurface 63 of the latch block. A downwardly projecting latch lug 64 is formed on the latch block including an included edge portion 65 facing the lever 12. The extremity 66 of the lug 64 nearest the fulcrum stud 61 is slabbed at right angles to the undersurface 63 and provides a latch surface adapted to retain the lever 12 in the position in which the springs 11 and 13 are stressed as illustrated in FIGS. 5 and 5A.

Extending upwardly from the latch block 60 and through a clearance aperture 67 in the mounting plate 55 is an operating pin 68 which is biased toward the lever 12 by means of a light spring 69 anchored on the mounting plate 55.

Fulcrummed on a screw 70 on the mounting plate 55 is an operating lever 71 for the latch block 60. Although the operating lever may be formed as an integral piece, it is preferably made in two parts including an arm 72 engaging the pin 68 and an arm 73 which is operated to release the latch block when the cam selection mechanism is operated. Preferably the arm 73 is formed with a pair of elongate apertures 74 and 75 one embracing the fulcrum screw 70 and the other providing a clearance slot for a clamp screw 76 threaded into the arm 72. By this means a limited adjustment of the range of portions of the arm 73 is possible.

The lever arm 73 is positioned in the path of an operating sleeve 77 which is slidable lengthwise along the shaft 36 and formed with a lateral projection 78 including an inclined conically shaped segment 79 adapted to engage and shift the lever arm 73. A light coil spring 80 arranged between the crank arm 40 and the sleeve 77 biases the sleeve against the bracket 45 so that the sleeve will be shifted along the shaft 36 to the left as viewed in FIG. 4 whenever the cam selecting handle 47 is depressed. The sleeve 87 is also formed with a lengthwise elongate aperture 81 embracing a pin 82 projecting radially from the shaft 36 so that the sleeve 77 will be shifted with the shaft 36 whenever the cam selecting handle 43 is depressed. When either of the cam selecting handles 43 or 47 is depressed, therefore, the sleeve 77 will actuate the operating lever 71 to turn the latch block 66 releasing the latch extremity 62 of the lever 12. The released lever 12 under the influence of the springs 11 and 13 will turn into the posit-ion illustrated in FIGS. 6 and 6A, and as long as either of the handles 43 or 47 remains depressed by the machine operator, the extremity 62 of the lever will be urged by gravity against the undersurface 63 of the latch block. In this position, the bias of the springs 11 and 13 will be removed from the wobble plate 9 and this the cam followers 16 and 17 may be shifted free of the spring influence.

Depending from the latch extremity 62 of the lever 12 is a cylindrical follower lug 85 adapted to cooperate with a cam 86 secured as by a screw 87 to the main shaft 22 to return the lever 12 to the latched position thus to reestablish the bias of the springs 11 and 13. The length of the lug 85 is such that as long as the latch extremity 62 of the lever remains in engagement with the undersurface 63 of the latch block, the lug 85 will remain above and radially outwardly of the cam 86. The bias effect of the springs 11 and 13 may, therefore, be released regardless of the position of rotation of the sewing machine main shaft. When the handles 43 and 47 are released after cam selection has been effected, the sleeve 77 will be retracted by the spring 80 and the spring 69 will return the latch block 60 into the position illustrated in FIGS. 7 and 7A. This movement of the latch block will shift the latch extremity 62 of the lever 12 along the inclined edge 65 and onto the latch lug 64 and in so doing will depress the lever 12 bringing the cylindrical lug 85 into the path of the cam 86. On subsequent operation of the machine, turning of the main shaft will, therefore, cause the cam 86 to return the lever 12 as illustrated in FIGS. 7 and 7A until the lever extremity 62 rides off the latch surface 66 of the lug 65 into the fully restored position illustrated in FIGS. 5 and 5A wherein the springs 11 and 13 will again be effective.

Since the lever 12 may be released from the latch surface 66 of the latch block in any position of the main shaft, the degree of rotation of the main shaft necessary to restore the lever may vary. Consequently, when the cam positions are selected, for instance, for straight stitching and a throat plate with a restricted needle aperture is substituted, the needle may partake of a work penetration before the springs 11 and 13 are restored. To prevent needle damage in this event, a bracket 90 is secured to the machine frame and provided with lugs 91 defining bearings pivotally supporting a U-shaped wire spring 92. The upper arm 93 of the spring 92 is disposed adjacent to the bracket 45 of the selector mechanism for the cam follower 17 to be engaged and shifted thereby only when the bracket assumes One extremity of its possible range of angular positions about the shaft 36. In this position of the bracket 45 the corresponding position of the cam follower 17 corresponds to a cam selection dictating straight stitching. The lower arm 94 of the spring 92 extends adjacent to the pivot pin for the wobble plate 9 and when the bracket engages and shifts the spring arm 93 as illustrated in FIG. 8, the spring arm 94 will engage and lightly bias the wobble plate and hence the cam followers 16 and 17 into tracking relation with the cams in the cam stack 18. In all other positions of the bracket 45, the spring 92 will be out of engagement therewith and consequently, the spring will remain idle without biasing influence upon the cam followers in all but the straight stitching position of adjustment of the cam selection mechanism.

Having thus set forth the nature of this invention, what is claimed herein is:

1. A cam selecting mechanism for a sewing machine having an endwise reciprocable and laterally jogging needle, actuating mechanism including a rotary shaft for imparting endwise reciprocation to said needle, and needle jogging mechanism including a plurality of coaxially arranged pattern eams, a cam follower, operator influenced means for shifting said cam follower and said pattern cams relatively to establish said cam follower in tracking relation with any selected one of said pattern cams, needle jogging linkage responsive to pattern cam influenced movement of said cam follower, and spring means for biasing said needle jogging linkage into operative engagement with said cam follower, an anchor member for said spring means shiftably supported in said sewing machine, a shiftable latch block for constraining said anchor member in a position in which said spring means is effective, a restoring cam means driven by said rotary shaft for shifting said anchor member into a position of constraint by said latch block, and operator influenced latch release means effective in any position of rotation of said rotary shaft for shifting said latch block to release said anchor member from said position of constraint.

2. A cam selecting mechanism as set forth in claim 1 in which an operative connection exists between said latch release means for shifting said latch block and said operator influenced means for shifting said cam follower and said pattern cams relatively, whereby said latch release means is operated upon initiation of said operator influenced means.

3. A cam selecting mechanism as set forth in claim 1 in which said anchor member comprises a lever supported on a universal pivoted fulcrum on said sewing machine, and including a lever arm extending between said restoring cam and said latch block, means constantly urging said lever arm into engagement with said latch block, said latch block being shiftable so as to carry selectively into engagement with said latch lever a first abutment surface positioning said lever arm out of engagement with said restoring cam means, and a second abutment surface projecting from said first abutment surface toward said restoring cam means for urging said lever arm into engagement with said restoring cam means, said second abutment surface terminating in a latch surface effective to constrain said anchor member in a position in which said spring means is effective.

4. A cam selecting mechanism as set forth in claim 3 in which said latch block is pivoted relatively to the sewing machine on an axis substantially perpendicular to said rotary shaft.

5. In a cam selecting mechanism as set forth in claim 1, an auxiliary spring means for biasing said needle jogging linkage into operative engagement with said cam follower, and means effective in one selected position of said operator influenced means for shifting said cam follower and pattern cams relatively for rendering said auxiliary spring means effective.

6. In a cam selecting mechanism as set forth in claim 5 in which said operator influenced means for shifting said cam follower and said pattern cams relatively includes one station dictating the formation of straight stitches by said sewing machine, and in which said auxiliary spring means is rendered effective only in said one station of said operator influenced means.

References Cited UNITED STATES PATENTS 3,191,559 6/1965 Marsh et al 112158 RICHARD J. SCANLAN, I 11., Primary Examiner. 

1. A CAM SELECTING MECHANISM FOR A SEWING MACHINE HAVING AN ENDWISE RECIPROCABLE AND LATERALLY JOGGING NEEDLE, ACTUATING MECHANISM INCLUDING A ROTARY SHAFT FOR IMPARTING ENDWISE RECIPROCATION TO SAID NEEDLE, AND NEEDLE JOGGING MECHANISM INCLUDING A PLURALITY OF COAXIALLY ARRANGED PATTERN CAMS, A CAM FOLLOWER, OPERATOR INFLUENCED MEANS FOR SHIFTING SAID CAM FOLLOWER AND SAID PATTERN CAMS RELATIVELY TO ESTABLISH SAID CAM FOLLOWER IN TRACKING RELATION WITH ANY SELECTED ONE OF SAID PATTERN CAMS, NEEDLE JOGGING LINKAGE RESPONSIVE TO PATTERN CAM INFLUENCED MOVEMENT OF SAID CAM FOLLOWER, SAID SPRING MEANS FOR BIASING SAID NEEDLE JOGGING LINKAGE INTO OPERATIVE ENGAGEMENT WITH SAID CAM FOLLOWER, AN ANCHOR MEMBER FOR SAID SPRING MEANS SHIFTABLY SUPPORED IN SAID SEWING MACHINE, A SHIFABLE LATCH BLOCK FOR CONSTRAINING SAID ANCHOR MEMBER IN A POSITION IN WHICH SAID SPRING MEANS IS EFFECTIVE, A RESTOR- 